I recently wrote to the Ultimarc guy and asked the same question, and some others. Here are my questions and Andy's answers:
I plan to order an I-Pac2 with a PS/2 connector, and a serial Opti-Pac. Will both these devices work with DOS?
Yes these will be fine in DOS.
Can the I-Pac supply power to two Happ Perfect 360 joysticks and one 5v LED?
Yes, but it's easier to get this from the Opti-PAC, as this has 5v screw connections.
How can I make the regular mouse and the trackball both work? Will the Opti-Pac help me out with this? I would like the trackball and mouse to both be active at once and control the same cursor.
This is easy in Windows, but in DOS you would need to load/unload mouse drivers using batch files, with the correct switches for enabling a PS/2 or serial mouse.
Is it possible to wire two buttons to act as mouse buttons and keypresses at the same time? For example, when an arcade button is pressed, can it generate a mouse button signal and a keypress signal simultaneously?
Yes, you can connect buttons to both the Opti-PAC and I-PAC to do this.
As you can see, Andy takes the time to answer every question thoroughly.
Regards,
Dave